Havana , Cuba -LRB- CNN -RRB- -- If Diana Nyad never realizes her dream of swimming the Florida straits , it wo n't be for lack of trying . The 64-year-old began her fifth and last bid to swim from Cuba to the United States on Saturday morning .

Previous attempts were thwarted by dehydration , ocean currents and excruciating jellyfish stings to her tongue .

`` There 's the fine line between seeing that things are bigger than you and letting your ego go , '' Nyad said at a news conference in Havana Friday . `` And there 's another edge over that fine line where you do n't ever want to give up and I am still at that place ! ''

Were Nyad to swim the 103 miles from Havana to the Florida Keys , she would be the first person to do so without the benefits of a shark cage , flippers or wet suit .

And it would validate her attempts , which have spanned 35 years .

In 1997 , Australian endurance swimmer Susie Maroney , then 22 , completed the swim from within a shark cage .

Along with the protection the cage offers against toothy predators , swimmers say the cage provides a barrier against waves and other weather hazards .

Since Maroney 's swim , some of the world 's best endurance swimmers have tried to cross the straits of Florida without using a cage . All have been turned back .

But few have done so as persistently or as colorfully as Nyad .

The Key West , Florida , resident says she feels a special bond with Cubans and hopes her repeated efforts to swim between the two countries will help improve the still-tense relations between Havana and Washington .

Nyad often tried to communicate in rudimentary Spanish during the news conference Friday . She has said that during her long swims , she sings the Cuban ballad , `` Guantanmera , '' to herself hundreds of times .

Cuban authorities said that after her latest attempt was announced in state media , they received a barrage of suggestions from across the island on how she could ward off the stinging jellyfish that ended previous attempts .

This time , Nyad said , she will wear surgical gloves and a specially designed prosthetic face mask to prevent the jellyfish from stinging her .

`` It took us a year , we made mold after mold , '' Nyad said of the mask , adding it was the kind used to protect people who had suffered injuries to their faces .

`` It 's a two-edged sword for me . It 's cumbersome , it 's difficult to swim with , but it does n't matter . I am safe . There 's no other way . ''

Nyad will be accompanied by a 35-member crew aboard two sail boats . They will monitor her health , update her progress on social media and try to ward off sharks that might view her as a potential snack .

If all goes to plan , Nyad said , the swim will take her three days to finish .

CNN 's Matt Sloane contributed to this report .

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Her attempts started 35 years ago

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She hopes to swim the 103 miles from Havana to the Florida Keys

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If she 's successful , she 'll be the first person to do so without a shark cage , flippers or wet suit

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During her long swims , she sings Cuban ballad , `` Guantanmera , '' to herself